---
id: article-728f1fdd58e35722
locale: en
date: '2026-04-04T10:00:00.000Z'
title: >-
  Complete Guide: Basal Metabolic Rate, Total Energy Expenditure and Caloric
  Deficit
summary: >-
  Learn what basal metabolic rate (BMR) is, how to calculate your total daily
  energy expenditure (TDEE) and how to use this data to plan a caloric deficit,
  lose fat or gain muscle more effectively.
category:
  - Nutrition
  - Fitness
  - Health
thumbnail: /images/posts/imin-blog.png
---

## Complete Guide: Basal Metabolic Rate, Total Energy Expenditure and Caloric Deficit

If you want to manage your weight intelligently, whether to lose fat, gain muscle mass, or simply maintain your current body composition, you need to understand two fundamental concepts: **basal metabolic rate (BMR)** and **total daily energy expenditure (TDEE)**.

In this guide, we explain everything you need to know clearly and practically, and you will also see how to use this data to plan a **caloric deficit** more thoughtfully.

### What is basal metabolic rate (BMR)?

The **basal metabolic rate** is the minimum amount of energy (measured in calories) your body needs to function at complete rest. This includes vital processes such as breathing, heart pumping, brain activity, body temperature regulation, and cell renewal.

BMR accounts for approximately **60% to 75%** of all the calories you burn each day. This means that even if you spent the entire day without moving, your body would still use a significant amount of energy just to stay alive.

### Factors influencing your BMR

Your basal metabolism is not a fixed number; it depends on several variables:

- **Body weight:** the higher the weight, the higher the BMR, because there is more tissue to maintain.
- **Height:** taller people have a larger body surface area and therefore a greater basal energy expenditure.
- **Age:** BMR decreases with age, approximately 1-2% per decade after 20 years old, mainly due to progressive muscle mass loss.
- **Sex:** men usually have a higher BMR than women of the same weight and height, due to a greater proportion of muscle mass.
- **Body composition:** muscle tissue consumes more energy at rest than fat tissue. Therefore, people with higher muscle mass have a higher BMR.

### How to calculate BMR: Mifflin-St Jeor formula

There are several formulas to estimate basal metabolism, but the **Mifflin-St Jeor formula** (1990) is the most recommended by the scientific community for its accuracy. This is the formula we use in our [BMR calculator](/en/calculators/bmr-tdee).

**For men:**
BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5

**For women:**
BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161

#### Practical example

A 30-year-old man, weighing 80 kg and 178 cm tall:

BMR = (10 × 80) + (6.25 × 178) − (5 × 30) + 5 = 800 + 1112.5 − 150 + 5 = **1767.5 kcal/day**

This means his body requires approximately 1768 calories daily just to maintain vital functions, excluding any physical activity.

### Other formulas: Harris-Benedict and Katch-McArdle

Although we recommend Mifflin-St Jeor, it’s useful to know the alternatives:

**Harris-Benedict (revised):** was the standard formula for decades. It is slightly less accurate than Mifflin-St Jeor, especially in overweight or obese individuals.

**Katch-McArdle:** accounts for lean body mass (fat-free), making it more precise for people who know their body fat percentage. The formula is: BMR = 370 + (21.6 × lean mass in kg).

### What is total daily energy expenditure (TDEE)?

BMR only counts the calories you burn at rest. Throughout the day, your body uses additional energy for:

1. **Physical activity:** from walking to intense training.
2. **Thermic effect of food (TEF):** the energy your body uses to digest, absorb, and process nutrients. This accounts for about 10% of the total.
3. **Non-exercise activity thermogenesis (NEAT):** involuntary movements, gestures, posture changes, and daily activities.

The **total daily energy expenditure (TDEE)** is the sum of all these components. To calculate it practically, multiply your BMR by an **activity factor**:

| Activity Level       | Factor | Description                                      |
|----------------------|--------|--------------------------------------------------|
| Sedentary            | 1.2    | Office work, little or no exercise               |
| Lightly active       | 1.375  | Light exercise 1-3 days per week                  |
| Moderately active    | 1.55   | Moderate exercise 3-5 days per week               |
| Very active          | 1.725  | Intense exercise 6-7 days per week                |
| Extra active         | 1.9    | Professional athlete or very intense physical work |

#### Practical example (continued)

If our 30-year-old man trains 4 days a week with moderate intensity:

TDEE = 1768 × 1.55 = **2740 kcal/day**

This is his estimated total daily calorie expenditure.

### What is a caloric deficit?

A **caloric deficit** occurs when you consume fewer calories than you burn. In practice, TDEE is the starting point for calculating it.

Example:

- TDEE: 2740 kcal/day
- moderate deficit: 2240-2440 kcal/day

This reduction is usually more sustainable than an extreme cut. If you want to dive deeper into how to approach it without losing strength or adherence, also read our guide on [caloric deficit](/en/blog/calorie-deficit-what-it-is-how-to-calculate-it-and-how-to-do-it-without-losing-strength).

### How to calculate a realistic caloric deficit from TDEE

A simple way to start:

- **Mild deficit:** subtract 200-300 kcal
- **Moderate deficit:** subtract 300-500 kcal

The more aggressive the cut, the harder it is to maintain:

- energy
- performance
- consistency
- muscle mass

That’s why for most people a moderate deficit with strength training and good protein intake works best.

### How to use your TDEE to reach your goals

Once you know your total energy expenditure, you can adjust your diet precisely:

**To lose body fat:**
Consume 300 to 500 calories less than your TDEE. This moderate caloric deficit will allow you to lose around 0.3 to 0.5 kg of fat per week sustainably, preserving your muscle mass as much as possible.

Using our example: 2740 − 400 = 2340 kcal/day for cutting.

**To gain muscle mass:**
Consume 200 to 400 calories more than your TDEE. This controlled surplus provides the extra energy needed for protein synthesis and muscle growth.

Using our example: 2740 + 300 = 3040 kcal/day for bulking.

**To maintain your weight:**
Consume calories equal to your TDEE. Ideal for maintenance phases or body recomposition.

### Common mistakes when calculating basal metabolism

- **Overestimating activity level:** many people classify themselves as "very active" when they are really "moderately active." Be honest with your assessment.
- **Ignoring changes:** your BMR changes as you gain or lose weight. Recalculate every 4-6 weeks.
- **Too aggressive deficit:** eating far below your BMR can slow your metabolism, cause muscle loss, and affect hormonal health.
- **Not considering body composition:** two people with the same weight may have very different BMRs if one has more muscle than the other.

### How to increase your basal metabolic rate

If you want to naturally boost your BMR, these science-backed strategies help:

1. **Train strength regularly:** muscle is metabolically active and increases your BMR long-term. Calculate your [one-rep max](/en/calculators/one-rep-max) to optimise your workouts.
2. **Consume enough protein:** protein has the highest thermic effect of all macronutrients (20-30% of its calories are spent digesting it).
3. **Sleep well:** lack of sleep reduces BMR and increases hunger hormones. Calculate your [recovery time](/en/calculators/recovery-time) to rest enough between sessions.
4. **Stay hydrated:** dehydration can lower your metabolism. Use our [hydration calculator](/en/calculators/hydration) to know how much water you need.
5. **Move more throughout the day:** increasing your NEAT can add hundreds of calories burned daily.

### Common errors when using BMR and TDEE

- **Thinking they are exact numbers:** these are useful estimates, not a perfect reading of your metabolism.
- **Calculating once and forgetting:** if your weight, activity or goal changes, it’s wise to recalculate.
- **Using the number out of context:** TDEE serves to make decisions, not to obsess over every calorie.
- **Creating an overly aggressive deficit:** if you cut too much, maintaining strength, energy and adherence becomes harder.

### Calculate your BMR now

Ready to know your numbers? Use our [basal metabolic rate and total daily energy expenditure calculator](/en/calculators/bmr-tdee) to get your results in seconds. It's free and requires no registration.

If your goal is fat loss, the logical next step is this guide on [how to do a caloric deficit](/en/blog/calorie-deficit-what-it-is-how-to-calculate-it-and-how-to-do-it-without-losing-strength) without losing strength or making the process unsustainable.

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